Various functions, such as an anti-scratch function, a function for preventing external light reflection, and an anti-soiling function, are required on a surface of a display such as a CRT (Cathode Ray Tube) display, an LCD (Liquid Crystal Display), a PDP (Plasma Display Panel), and an EL (Electroluminescence) display.
In an example of a method for providing a function for preventing external light reflection, LR (Low Reflection) treatment is implemented by providing a material having a different refractive index to that of a material constituting the display as a film on a surface of the display such that reflection is reduced by an interference effect between light reflected by the display surface and light reflected by the film surface.
However, reflection on an interface between air and the film surface and reflection on an interface between the film surface and the display surface typically deviate from ideal conditions in terms of respective amplitude reflectance values and phase values thereof. Hence, reflected light resulting from the reflection is not cancelled out completely, and as a result, a sufficient antireflection effect is not realized. Therefore, with LR treatment alone, peripheral light is reflected at a constant reflectance so that images from a light source such as a fluorescent lamp are reflected on a display, making the display extremely difficult to see. In response to this problem, AG (antiglare) treatment for preventing external light reflection using a light scattering effect is implemented additionally by forming a fine concave-convex pattern on the surface of the display so that images from a light source such as a fluorescent lamp are blurred by the scattered light.
In an example of a typical method for forming a fine concave-convex pattern, a relief hologram or a diffraction grating such as that applied to credit cards, ID cards, gift certificates, banknotes, and so on for security purposes, for example, is formed (see Patent Documents 1 and 2, for example). Patent Documents 1 and 2 describe a 2P (Photo Polymer) method in which a transparent backing such as a polyester film is coated with a liquid photo-curable resin composition to form a liquid photo-curable resin layer, a stamper having a fine concave-convex pattern is pressed onto the photo-curable resin layer, and in this condition, the photo-curable resin layer is hardened by emitting light from the backing side, whereupon the stamper is removed, and a method of coating a backing with a photo-curable resin composition that is highly viscous or solid at room temperature to form a liquid photo-curable resin layer, pressing a stamper onto the photo-curable resin layer, peeling away the photo-curable resin layer, and then hardening the photo-curable resin layer by emitting light thereon.
Incidentally, in recent years, moth-eye structures, with which a super antireflection effect can be obtained without using optical interference, have come to attention as a method of realizing low reflection on a display surface through means other than AG treatment. In a moth-eye structure, a finer concave-convex pattern than that used in the AG treatment, having intervals that are no greater than the wavelength of light (no greater than 380 nm, for example), is arranged continuously on the surface of an object to be subjected to antireflection treatment such that the refractive index on the interface between the outside (air) and the film surface varies quasi-continuously. Thus, substantially all light is transmitted irrespective of the refractive index interface, and as a result, light reflection on the surface of the object can be substantially eliminated (see Patent Documents 3 and 4, for example).
Patent Document 1: Japanese Patent Application Publication No. 2004-59820
Patent Document 2: Japanese Patent Application Publication No. 2004-59822
Patent Document 3: Published Japanese Translation of PCT Application No. 2001-517319
Patent Document 4: Published Japanese Translation of PCT Application No. 2003-531962
Following various investigations into antireflection films (also referred to hereafter as moth-eye films) having a moth-eye structure on a surface thereof, the present inventors found that, depending on constitutional materials and manufacturing conditions of the moth-eye films, light may be scattered on the moth-eye structure, and as a result, when the moth-eye film is adhered to a surface of a display device, for example, an image displayed by the display device may appear cloudy.